1. Field of the Invention
This invention relates to a rubber track assembly for use in construction equipments, agriculture machineries, civil engineering machineries and the like.
2. Description of the Prior Art
A conventional rubber track assembly is shown in FIG. 1. Such a rubber track assembly comprises a driving sprocket wheel 1, an idler wheel 2, an endless rubber track 3 which extends around the driving sprocket wheel 1 and the idler wheel 2, and a plurality of roller wheels 4 arranged in contact with the inner surface 5 of a ground contact region of the rubber track 3 between the driving sprocket wheel 1 and the idler wheel 2.
Furthermore, a conventional rubber track 3 has a plurality of rubber lugs 6 formed on its outer circumference 7, a plurality of rubber guide projections 8 formed on the inner surface 5 to protrude at the central region thereof and spaced to each other by a predetermined distance in the longitudinal direction of the rubber track 3, and steel cords 9 embedded in the rubber material 10 and extended in the longitudinal direction of the rubber track 3 as shown in FIG. 2.
Each of the wheels 1, 2 and 4 has a pair of wheel portions 11 spaced to each other in a direction of the width of the rubber track 3 to contact the inner surface 5 of the rubber track at opposite sides of the rubber guide projection 8 as shown in FIG. 2.
The driving sprocket wheel 1 also includes a plurality of driving members 12 such as drive pins, teeth or the like disposed between the wheel portions 11 and adapted for engaging the guide projections 8 to drive the rubber track 3.
The conventional rubber track assembly has a disadvantage in that when the rubber track assembly is cornering along a curve, the wheel portion 11 is forcedly moved in a lateral direction shown by an arrow A in FIG. 3, and the wheel portion 11 laterally pushes an inclined side surface 8a of the rubber guide projection 8 on the rubber track 3 so that the rubber track is subjected to a side force f which consists of a horizontal component fx and a vertical component fy. Since the side surface 8a of the rubber guide projection of the conventional rubber track assembly is made of rubber having a high coefficient of static friction such as .mu.=0.5, the vertical component fy cannot cause a sufficiently high horizontal component fx sufficient to overcome the force of friction F between the rubber track 3 and ground G. Accordingly, the wheel 1, 2 or 4 climbs the inclined side surface 8a to trample over the guide projection 8 and, as a result, the wheel is derailed from the rubber track 3, or the guide projection 8 is damaged by the wheel. Also, energy losses are caused by the substantial traveling resistance.